Narcissistic characteristics can also be found in many members of the gay and transgender community. What marks out the gay community from heterosexuals is their use of their sexuality in itself as a way to mark themselves as different. In other words, their sexuality is used as a way to express their narcissism (as described here) - their sexuality is the physical manifestation of their narcissism. However, this is not to say that they are inherently more narcissistic than a heterosexual narcissist - merely that the narcissistic manifestation is more distinctly expressed.
The link between homosexuality and narcissism is unclear, as there has been little proper scientific research into this area. It would be unfair to delve into any controversies about the origins of homosexuality per se. There is a plethora of evidence that homosexuality occurs naturally throughout the animal kingdom. That is not so say, though, that there may well some biological cross-over between homosexuality and narcissism. But due to a lack of actual scientific evidence thus far, this can only be conjecture. For this reason, what is said below is based on some element of supposition.

However, it can be said that due to the way that homosexuals define themselves by their body (and sexual identity), they may also be somatic narcissists (i.e. they are in love with their own body). Likewise, it could be argued that a homosexual may be in love with his own idealised image of himself, and that this is what he seeks when he seeks a sexual partner. He or she is attracted to the person that most correlates to the person he or she wishes to be, consciously or not. Therefore, having this person as a partner is the ultimate form of self-love as well as - in a manner of speaking - auto-erotica. In the same way that the heterosexual somatic narcissist uses a member of the opposite sex to essentially masturbate into, the homosexual narcissist enjoys his/her partner as a way to effectively achieve sexual pleasure from their idealised self in physical form.
The narcissism that exists in the homosexual may more generally manifest itself in other ways. Some homosexuals enjoy having a single long-term partner (which may mark them out as being a cerebral narcissist - see the link mentioned earlier), while others may repress their homosexuality for years and living with a sheltered secrecy to their sexuality, which is revealed only in carefully-orchestrated situations (this may also be a marker of cerebral narcissism of a kind). Yet again, many homosexuals will themselves openly admit to being promiscuous (justifying this by saying "it's a very promiscuous scene"), which is another sign of ingrained somatic narcissism: promiscuity is a symptom of narcissism as narcissists quickly bore of "routines", as it goes against his sense of uniqueness and entitlement. Homosexuals are often histrionic ("drama queens"), and some also indulge in other forms of outrageous showmanship, such as cross-dressing. These are all methods of achieving attention and limelight - forms of narcissistic supply, as true with any classic narcissist.

Bisexuality may also, in another way, be seen as a manifestation of narcissism. As a homosexual can be said to seek sex from an idealised image of himself, the bisexual could be said to literally want the best of both worlds - both male and female - and therefore wants to take their sexual omnipotence to the ultimate heights. By seducing and "conquering" both males and females, the bisexual narcissist boosts his self-image by feeling loved by both sexes, which makes him/her feel like God - in an almost literal sense. They may feel they have defied "nature" itself by being sexually-attractive to both sexes simultaneously

The psychology (and narcissism) of transsexuals is perhaps more contorted still. Transsexuals seek to change their gender as they reject their own sense of self. While there are various motivations for this, it can be said that this motivation shares characteristics with the same narcissistic motivations that can be seen in aspects of homosexuality i.e. as the homosexual is attracted to an idealised version of himself he sees in another person, the transsexual sees an idealised version of himself in a member of the opposite sex, and seeks to become that person. In other words, the transsexual rejects his own gender completely, in order be become another (idealised) version of himself in the opposite gender. This can also be called a narcissistic psychology due to the unrealistic nature of this fantasy or wish, as it involves such a drastic (and possible unobtainable) step. Also, this shows the objectification of the transsexual's own body, in a way far more pronounced than can be seen in a homosexual.
Some transsexuals (known as autogynephilic) even wish to change their gender in order to become the sexual object of their own desire. Thus, they may attract members of the opposite sex to themselves in order to fulfill the fantasy of somehow taking on both roles in the act of sex, the male and the female. It can then also be argued that transsexuals have a grandiose sense of entitlement, owing to the nature of their psychology. They feel they deserve to be taken care of by society and their fantastic (biologically-demanding) wishes to be fulfilled, and will go to extreme lengths to do so; in some cases being highly histrionic and even threatening self-harm if they fail to get what they want.

To summarise, the psychologies of the LGBT community seem to be skewed towards some form of expression of narcissism, but may simply be more contorted manifestations of narcissism; a variant on the heterosexual manifestation.

The last taboo

However, narcissism takes on an utterly amoral form when it is manifested in the form of child abuse. There have been numerous examples of this psychology laid bare in the UK, with the revelations regarding Jimmy Savile, as well as the former LostProphets' singer, Ian Watkins. This manifestation of amoral narcissism is ultimately psychopathic in nature, as well as highly-narcissistic - and has almost certainly nothing to do with sex. Along with the sexual sadist, these types of individuals' acts are simply a way of demonstrating their amoral omnipotence. As children are seen as something innocent and rightfully protected by law, therefore these individuals feel they wish to make a point by showing their disdain for moral values. This same type of pathology was evident in the psychology of the serial killer, Ian Brady. These individuals' enormous sense of entitlement, wishing to omnipotent and callously objectify their victims, is the ultimate expression of their deep, dark narcissism.
Along with those in positions of power, this form of sexual psychopathy and deep-rooted narcissism is perhaps the most frightening of all - barring serial killers.